Contraangle handpiece



Aug. 4, 1925. 1,548,180

. R. W. BROWN ET AL 4CONTRAI ANGLE HANDPI ECE Filed Apg. 23. 1924 I 2 Sheets-Smet 2 invented new and useful drels,

Patented Aug.v- 4, 1925.

UNITED sTATEs PATENT ljoFFlca.

BAY BIBUWN AND ANDREW I. SPINKS, 0F LOS ANGELIS, CALIFOBNA.

ooN'raAANGLT-i nnmrmcn.

Application led August 23, 1924. Seriallo. 733,783.

To all whom it may concern:

j Be it known that we, RAY'W. BROWN and ANDREW M. SPINKS, citizens of the United States, and residents of Los Angeles, county of Los Angeles, State of California, have Improvements in Contraangle Handpieces, of which the following isa specification.

This invention relates to dental instruments and particularly to hand-pieces.

In the preparation of teeth that are 'shaped externally, or internally, by one or lanother of various 4grinding or abrading tools such as burrs, drills, abrasives, manburmshers, reamers, facers and mounted points, rotatively operated at a'pretty i good speed, various mechanisms have been of lateral and end play.

proposed, and some are marketed, for enabling the easy and quick change and application of the desired tools to the driving hand-piece of the mechanism. A common form of hand-piece, of the contra-angle attachment type,vis shown as an example ofl the art. An objection to variousv forms of hand-pieces, now sold, is an excessive amount When a cavity is prepared to form a nearly parallel faced matrix, quently results in -so undercutting a cavity face that, though the matrix can be taken olf, the cast metal matrix producty cannot be fitted onto the tooth body with desired perfection of attachment.

Again, because ofa very great deficiency of bearing area of the parts which have a. relative high speed action the parts very quickly wear and thus rapidly increase e initially too great amount of play.

An object ofy this invention is to overcome the excessive looseness of the attached cutting toolin thehead or angle piece andto reduce it to a totally negligible amount, actually necessary in order to allowdriving rotation lof the tool without anymaterial friction a heating, which latter results from friction of high s eed in running parts having a totally insu cient bearing of ro-Y the lost movement in lthe tool fre.

longitudinal section o A further object is to provide means for holding the tool in a true central and nonwobbling position in its bearing.

-An object is to provide. a hand piece having a housing which has no removable bottom bearing and thus to avoid the liability of any part of the housing from working loose and falling away from the tool.

An important object is to provide a hand piece having bearing surfaces of ample and large area to secure durability, as well as to produce a tool having practically no play.

An object is to provide a driven gear of good sizeto achieve greater number of tooth mesh, and this without objectionable size of housing. Y

A very important object is 4to provide for the mounting of the removable tool shank" the shank, and of the sleeve or shaft, this play being a serious Isource of annoyance.`

vAn object is to provide for the take up of wear of the end-thrust of the parts by provision of a lockable, shiftable bearing in the housing. And in object is to provide means for so holding the gearhaft that the gear teeth cannot be jammed up'into the driving pinion with unnecessary pressure.

Y An object is to provide a hand piece in which a hollow gear-shaftand an inserted 'tool shank are secured to act as a one-piece unit, and to provide a device positively 1nterlocking with'the driven gear shaft.

Other objects and' advantages will be made manifest 1n this connection, an I the body of y the following specification of an embodiment of apparatus of the invention; it being understood that other modifications, variations andadaptations may be resorted to within the spirit of the invention and its scope as here claimed The invention consists of structure whereby the objects are accomplished, and one structure isv illustrated in the accompanyingv drawings, wherein.:

Fig. 1 isa side elevation of the an lepiece, full size scale. Fig. 2 is a top p an of the housing, full size. Flg. 3 shows the drivingpinionand part of the attachshows tooth treat-l Fig. .4

ment, full size. a

ment with a grinding oint. Fig. 5 is a.

the .Ahead piece,

double size. Fig. 6 is a similar section, double size, of the housing. Fig. 7 is a plan of the housing. Fig. 8 is a plan of the collct-or draw-in nut, and Fig. 9 is a side View thereof. Fig. 10 is a plan of the bearing, and Fig. 11 is a side view thereof. Fig. 12 is a plan of the bearing lock-nut, and Fig. 13 is a side view thereof. Fig. 14 is a plan, and Fig. 15 is a partial section and elevation of the hollow gear shaft. Fig. 16 is an end view, and Fig. 17 is ay side elevation ofthe collet. Fig. 18 is a view of the jaw end of the collet. Fig. 19 is a side view of a mounted point tool. Figs. 20 to 25 inclusive are views of old parts, to show by comparison the differences in the apparatus of the present invention.

ln Fig. 4 there is shown a tooth stump being prepared by atool T known as a mounted point, and being but one of many kinds and varieties of tools having a shank S to be fitted in the handpiece housing H and rotatively driven. lt will be seen that any undue play of the tool defeats precision, accuracy and economic speed of work. Moreover looseness develops obnoxious noise during operation and this seems to be cruelly heard, through the teeth, by the naturally nervous patient. By the present invention much of the clatter of the instrument parts is eliminated, and the patient made more comfortable to his advantage and the doctors relief.

ln Figs. 20 to 25, inclusive, a construction l old in the art is shown and the causes of undue play in this construction will be explained. In the housing H (dotted lines) is a hollow shaft A having a driven gear to mesh with apinionll? (Fig. 3) The shank S of the tool T is designed to slip freely and readily into the shaft A and commonly has a lateral play of two or three one-thousandths of an inch which is multiplied at the tip of the tool when the shank tilts vobliquely in the shaft. The lower end Vof the housing receives a threaded ...bushing B in which the hollow shaft rotates. The working clearance, two or three thousandths, is added to that of the shank in the shaft and so much more play is given the shank sldewise.

The hollow shaft A has at its top end a small collar C presenting a small end face or thrust surface E to the upper shoulder in the housing. This shoulder forms a very narrow bearing-D laround the end of the shaft A. The very small areas B and E rapidly wear and increased play results, and

they heat from high s eed contact friction. l

The shaft has end p ay in the bearings. Shanks S' have necks S2 to receive a latch L, which is slotted at L to pass across the neck and so hold the shank against falling out. Much end play occurs at the latch L. The Shank S has a flattened head F to match gear contact results and with much lash so p that tooth impingement is noticeable. f The instrument of Figs. 20 to 25 is one of the best on the market, and has been constantly used by Dr. Spinks, a joint applicant here.

Fully cognizant of the requirements the invention seeks to .attain a more precisely operative and close running tool.

To that end the improved structure includes a housing H bored downward from its top end to form a large gear chamber contracted at its lower end to form a shoulder 2 and a long immovable bearing 3. The upper -end of the chamber. is threaded at t to receive an externally threaded bushing 5 whose top end is kerfed at 6 to take a screw driver by which the bushing may loe run in. From one side of this extends a box 7 threaded to receive a vnipple N (Fig. 3) of the usual driving shaft neck. lin front of the nipp'le/ is the driving pinion P which projects into the housing chamber to mesh with a driven gear 10. This gear 1() is rigid on a hollow shaft l1 which has a collar 12 whose upper end is engaged by the adjustable bushing 5 so that the lower end face of the gear can be set down with a running contact against the housing shoulder' 2. Thus all unnecessary end play is eliminated and is taken up by the bushing 5 as the end thrust faces vwear. The hollow shaft 11 has lar e bearing areas inV bearing 3 and in the bus ing 5 and only running clearance is permitted. As the bushing is turned in to take up Wear it is locked by a nut 13.

Means for securing the cutting tool shank S of a tool T comprises an elongated collet 14 having a tapered head 15 split at 16. The other end of the collet is threaded at 17, to

receive a draw-in nut 18, whereby the collet` head 15 may be pulled into the lower end of the hollow shaft 11, this being slightly countersunk lcomplementary to the head. The nutl18 is reversible and has reduced ends 19 to set against the near 'end of the Ihollow shaft.-

While the nut 18 is loosened u on the collet a tool shank S may be shove into the collet to any desired degree of projection of tool .point T. Then the nut 18 is turned in on the collet and as the nut runs against the hollow end, the collet will draw in and the collet jaw close upon the shank S and firmly hold it to rotate with the'hollow shaft.

To prevent any possibility of the nut accidentally unscrewing and thus releasing the tool T, the collet is grooved at 19 to slide past a lug or key 20 rigid in the hollow shaft. During operation no drive strain is put on the key 20 since the shank S is fricthe shaft and tionally but very firmly gripped by the contracted collet head-jaws.

The collet, the hollow shaft and the tool are all rigidly locked-to run asl one piece.

There is no play in these parts. The only possible lost motion is a minute end and side play for operative lit of the hollow shaft in its housing and bushing'bearings.

The hollow shaft has a large peripheral bearing at each end giving life. It has large end thrust surfaces closely fitted to prevent play.

The collet holds the shaft tru-e to and on axial centre line of the housing. The tool can be driven ineither direction without any danger of any parts falling out and into theV mouth of a patient. The removable bearing is at the top, and it is locked in.

What is claimed is:

l. A contra-angle dental hand piece including a casing having a lateral, tapped recess for a driving shaft attachment Aand having a generally cylindrical bore presenting an interior diametrical shoulder at right angles to the axis of the bore and forming a reduced axial bearing, a hollow shaft coextensive with the length of the casing and having a shoulder to bearvon the shoulder of the casing and having a gear on its opposite face, a collar near th'e opposite end of sitioned within the end of the casing, a rlng bushing to screw into the casing against the collar, a lock nut jamming on the bushing and against the casing, and a split clutch comprising a sleeve hollow from end to end for projection therethrough of an inserted tool shank and a drawing-in nut pressing against the said hollow shaft,

2. A contra-angle dental hand piece including a casing having a lateral, tapped recess for a driving shaft attachment and having a generally cylindrical bore presenting an interior diametrical shoulder at right angles to the axis of the bore' and forming a reduced axial bearing, a hollow shaft co-extensive with the length of the casing and having a shoulder to bear onthe shoulder of the casing and havinga gear on its opposite face, a collar near the opposite end 4 of the shaft and positioned within the end of the casing, a ring bushing to screw into the casing against the collar and extending therefrom to the end of the shaft, a lock nut jamming on the bushing and against the casing,"'and a splitJ clutch comprising a. sleeve hollow from end to end for projection therethrough of an inserted tool shank and having a draw-in nut pressing against the said hollow shaft; the sleeve having a generally uniform cylindrical bore from end to end for 'the shank of the tool.

- RAY. w. BROWN.

ANDREW M. SPINKS. 

